Barrons Publishing Dictionary of Computer and Internet Terms 10th

corresponds to Cairo; portions of the Cairo project appeared in versions ranging from Windows 3.1 to Windows Vista. Compare BLACKCOMB; CHICAGO; LONGHORN; MEMPHIS; WHISTLER.

cakebox (humorous) the round plastic box in which bulk recordable CDs are supplied.

calendar see GREGORIAN CALENDAR; JULIAN CALENDAR; JULIAN DATE; LEAP YEAR.

calibration adjustment of image values to ensure faithful rendering of colors and gray tones when output to a printer or imagesetter. The calibration loop should include your scanner, your monitor, your software, and the printer. The goal is to make sure that colors are treated identically by the scanner, the software, the screen, and the printer. See COLOR.

CALL

1.a statement in FORTRAN, PL/I, some versions of BASIC, and most assembly languages, which transfers control of execution to a subprogram. When the subprogram ends, the main program resumes with the statement immediately after the CALL. Languages such as C, Pascal, and Java perform calls by simply giving the name of the routine to be called. In line-numbered BASIC, subroutines are called with the GOSUB command.

2.computer-aided language learning, the teaching of foreign languages to people with the aid of a computer.

Call Waiting a service offered by many American telephone companies that makes your telephone beep if someone tries to call you while you are already using the telephone. You can then put the previous call on hold and switch to the incoming call. These beeps disrupt transmission of computer data by telephone. To make a call that will not be interrupted by beeps, dial *70, wait for a dial tone, and then dial the call in the usual way. If you are using a Hayes-compatible autodial modem, give the number 555-1212 as *70W555-1212 or *70,,555-1212.

callout the line and caption marking the specific parts of a labeled illustration. For examples, see Figure 298 at WINDOW on page 529.

-cam abbreviation for camera, especially a digital or video camera whose images are made available by computer network. For instance, a camera connected to the World Wide Web is a webcam; a camera mounted on a tower is a towercam; and a camera strapped to the back of a horse might be called a horsecam.

CAM (Computer-Aided Manufacturing) the use of computers in a manufacturing process. For example, a computer could store a three-dimen- sional representation of an object and then control the manufacture of the object by automated machinery. Some of the principles of CAM are the same as with computer-aided design (see CAD), and sometimes a system is referred to as CAD/CAM.

camel notation a way of combining words by running them together, capitalizing every word except the first: thisIsAnExample. A word written this way has a low head and one or more humps, like a camel. Contrast

PASCAL NOTATION. See INTERCAPS.

camera-ready copy artwork or printed pages that are ready to be photographed and offset printed. The camera will see only black and white, not shades of gray, so the camera-ready copy must be free of smudges, dust, and stray marks. Usually, pale blue marks do not photograph, and most other colors photograph as black.

camera, digital see DIGITAL CAMERA.

CAN-SPAM (Controlling the Assault of Non-Solicited Pornography and Marketing) a law passed by the U.S. Congress in 2003 (15 U.S.C. 7701) providing penalties for sending deceptive mass e-mails. The act required the Federal Trade Commission to investigate whether or not to establish a national Do Not E-mail registry, but the commission concluded that such a registry would not work and instead emphasized the need to establish a means to authenticate the origin of e-mail messages.

cancel

1.to stop the execution of a command. Most dialog boxes have a Cancel button. This clears the dialog box from the screen without taking any action.

2.to send a command deleting a message from a newsgroup or other public forum. (See NEWSGROUP.) It is important to know how to do this in case you post something that turns out to be redundant or misinformed. On Usenet, the cancellation does not take effect instantly because the cancel command has to travel to all the sites that received the original message. Normally, users can cancel only their own messages, but see CANCELBOT.

cancelbot (from cancel and robot; see BOT) a computer program that automatically cancels certain messages from a newsgroup or other public forum. Cancelbots often eliminate messages that are excessively large or are copied to excessive numbers of newsgroups (see SPAM).

Canon engine see ENGINE.

Capability Maturity Model a set of criteria developed by the Software Engineering Institute at Carnegie Mellon University for judging and improving the performance of a software development organization. The model recognizes five levels of maturity:

1.Initial: Developers work as rugged individualists, trying to emulate other successful software developers.

2.Repeatable: The work is planned and somewhat predictable.

3.Defined: The work is planned in some detail with a plan that can be, and is, followed.

4.Managed: The work is not only planned but measured; managers know whether the expected level of productivity is being achieved.

5.Optimizing: Based on measurements, the process is continually improved.

Many software companies never get past the initial stage, which is adequate for highly talented individuals but leaves the overall organization very dependent on their specific talent (compare HACKER, definition 1).

See also SOFTWARE ENGINEERING.

caps capital letters. THIS SENTENCE IS TYPED IN ALL CAPS. Contrast with MIXED CASE; LOWERCASE.

Internet tip: Don’t send e-mail or post to newsgroups with your message typed in all caps. Not only is it more difficult to read, but it seems as if you are shouting (all your words are emphasized).

Caps Lock a special keyboard key which acts like the Shift key for the letter keys. You do not have to hold it down; when Caps Lock is on, YOUR TYPING LOOKS LIKE THIS. A common mistake is to leave Caps Lock on when you wish to type normally. Then letters you wish to be capitalized are lowercase, but everything else is all caps lIKE tHIS. Some word processors have commands to correct capitalization errors of this sort.

CAPTCHA (Completely Automatic Public Turing Test to Tell Computers and Humans Apart) an on-screen device that presents a quiz requiring a human response, to prevent an automatic BOT from gaining access to a location, such as a web page selling tickets. The CAPTCHA often appears as a graphical image of a simple arithmetic problem or a word written along a wavy curve. The automated bot only sees a graphical image and can’t provide the answer to the math problem. One purpose of the CAPTCHA is to prevent ticket scalpers from using bots to purchase large amounts of tickets from Internet ticket sellers. However, software advances may allow the bot to solve the CAPTCHA quiz.

capture

1. to cause a picture or graphic to be saved as a bitmapped image. See

FRAME GRABBER; SCREEN SHOT.

2. to divert data from a serial or parallel port to a networked printer, a print spooler, or the like.

Carbon application, Carbonized application (on the Macintosh) a software package written to take advantage of new features of Mac OS X, but also compatible with Mac OS 9. Contrast COCOA APPLICATION.

carbon copy a copy of an outgoing electronic mail message kept by the sender or forwarded to someone other than the recipient. (See CC; BCC; FCC.) In pre-computer days, carbon copies were made in typewriters by placing a sheet of carbon-coated paper and an extra piece of plain paper behind the main document.

card

1. a medium for storing data, such as a FLASH MEMORY CARD, SECURE DIGITAL CARD, SMARTMEDIA, or COMPACTFLASH. See CARD READER.

2.a printed-circuit board, especially one designed to be added to a microcomputer to provide additional functions (see Figure 49).

3.see PUNCHED CARD.

FIGURE 49. Card (definition 2)

card reader

1.a device that enables a computer to read FLASH MEMORY CARDs, (SMARTMEDIA, COMPACTFLASH, and the like).

2.a device that enabled a computer to read PUNCHED CARDs.

CardBus the 32-bit version of the PCMCIA (PC CARD) bus. See also EXPRESSCARD and note there.

caret

1.The character ˆ, more properly called CIRCUMFLEX or HAT, which indicates exponentiation in some programming languages.

2.^ the proofreading symbol used to mark where something should be inserted. (Caret is Latin for “is missing.”)

3.the INSERTION POINT (i.e., the point on the screen where characters will appear when they are typed on the keyboard).

careware SHAREWARE that requests a donation to charity rather than a monetary payment to the author. See FREE SOFTWARE.

carpal tunnel syndrome a repetitive-use injury of the carpal tunnel (a nerve pathway in the wrist) that afflicts some typists. The main symptoms are numbness and tingling in the hand. Stretching exercises and medication help mild cases, but sometimes surgery is necessary to relieve the pain. To prevent carpal tunnel syndrome, take a break and stretch your hands frequently. Some typists find a padded wrist support to be helpful. See ERGONOMICS.

carriage return see CR.

carrier a signal that has another signal modulated onto it. For example, a modem transmits data through a telephone line by transmitting a continuous tone as a carrier. Variations in frequency and phase of the carrier

encode the binary data. DSL networks use a radio-frequency carrier to transmit data over phone lines.

cartridge a self-contained, removable part of a computer, usually small and contained in a plastic case. For example, laser printers often take toner cartridges (containing toner, i.e., ink). Game machines often accept software in plug-in cartridges.

cascade to arrange multiple windows so that they look like a stack of cards, with all but the top and left edges of each window hidden by the one in front of it (see Figure 50). When the windows on a screen are cascaded, you can see the title bar of every window. Contrast

OVERLAID WINDOWS.

FIGURE 50. Cascaded windows

cascading menu a menu that leads to more menus. For an example, see

START MENU.

cascading style sheet a set of HTML rules governing the appearance of a set of pages at a web site on the World Wide Web. Cascading style sheets use precedence rules to decide which of two commands should take effect in case of a conflict. See STYLE SHEET.

CASE (computer-aided software engineering) the use of computers to help with the process of designing software.

case

1.the property of being capitalized (uppercase, LIKE THIS) or lowercase (like this); so called because of the wooden cases in which printers’ type was stored in the 1800s.

2.a statement in Pascal that directs a program to choose one action from a list of alternatives, depending on the value of a given variable. Here is an example of a case statement:

CASE place OF

1 : writeln(’First place !!!’);

2 : writeln(’Second place’);

3 : writeln(’Third place’) END;

FIGURE 51. CCD image sensor (in webcam with lens removed)

CCD image sensor (charge-coupled device) the electronic image sensor most often used in digital cameras, video cameras, and scanners. A lens forms an image on an array of cells (Figure 52), each of which contains a photoconductive layer that accumulates a charge in proportion to the amount of light that falls on it. The accumulated electrons are then shifted from cell to cell until each cell’s value appears at the output. Scanners often use sensors in which the cells are in a line rather than a rectangular array.

CCDs record only the intensity of the light, not the color. In scientific work, color pictures are obtained by taking a set of black-and-white images through different filters. In most color digital and video cameras, adjacent pixels on the CCD contain pale red, green, and blue filters, so that a color image can be obtained all at once; the color of each pixel is interpolated from those around it. In rare cases this gives inaccurate color, as when photographing a distant zebra whose black and white stripes hit pixels with different color filtration. Contrast FOVEON.

Inherently, CCDs respond strongly to infrared light, but most of them contain extra layers to increase the response across the visible spectrum and cut the response to infrared. A CCD camera can often “see” the infrared beam from a TV remote control.

The main limitation of CCDs is that the cells conduct some electrons even in the absence of light, in a highly random manner. This shows up when the exposure is longer than about 5 to 10 seconds; the image is covered with speckles. The CCDs used for long exposures in astronomy are cooled to low temperatures to reduce this problem, and a sample of the noise itself (a long exposure with the shutter closed) is often digitally subtracted from the image.

See also CMOS IMAGE SENSOR; BAYER MATRIX.

FIGURE 52. CCD image sensor

CCITT (Comité Consultatif Internationale Télegraphique et Téléphonique) former name of international organization that sets standards for data communication, now known as ITU-T. See ITU-T; X.25.

ccTLD (country code Top Level Domain) a two-letter code indicating the country of an Internet address. For example, the web address for Oxford University is www.ox.ac.uk; here .uk is the country code for the United Kingdom. For a complete listing of the ccTLDs, see the tables on pages 552 to 554.

Most codes can be used only for sites in the countries to which they belong. However, some countries, such as Tuvalu, encourage the use of their country codes elsewhere, so long as the country’s own registrar gets the registration fees. For examples see .TV; .NU; .WS. See also GTLD.

CD (Compact Disc) a type of plastic optically readable disk introduced by Philips and Sony in the 1980s to store digitized music recordings. Subsequently, CDs have become popular as a way of storing computer files (see CD-ROM). The data on CDs is encoded in microscopic grooves and is read by scanning the rotating disk with an infrared laser beam. Conventional CDs are 12 cm (4.7 inches) in diameter. An 8-cm (3.15inch) size (“mini-disc”) is also used; it has about 1/5 the capacity.

Unlike a diskette, a CD has its data on one long spiral track, like the groove in a phonograph record; this simplifies the design of CD players. One CD can hold 75 minutes of audio (just enough for Beethoven’s Ninth Symphony, which was the design goal) or 680 megabytes of computer data. Newer CDs have slightly more capacity, 80 minutes or 700 MB.

Note the spellings disc for CDs versus disk for magnetic disks. See also RED BOOK; CD-ROM; DVD.

CD-E (Compact Disc—Erasable) an older name for CD-RW.

CD-R (Compact Disc—Recordable) a type of CD (compact disc) that can be recorded by the user. CD-Rs have the same capacity and are readable in the same drives as ordinary CDs (except for DVD drives—see DVD). Instead of being manufactured by pressing, CD-Rs are recorded by bleaching (“burning”) small areas of dyed plastic with a laser to create an appearance similar to the indentations in an ordinary CD.

CD-Rs are somewhat less durable than pressed CDs, though still more durable than most other computer media.

CD-ROM (Compact Disc—Read-Only Memory) an optical disk like an audio compact disc, but containing computer data. Audio and computer CDs are physically the same; in fact, a single CD can contain both computer files and music. CD-ROMs can only be read, not recorded on, by the user’s computer. CD-R and CD-RW are CD-ROM-compatible media that can be recorded on by the user.

Unlike diskettes, CD-ROMs are not tied to the operating system of a specific computer (although the software that is on them may be). Any computer can read the data on any CD-ROM. CD-ROM drives are rated for their speed compared with the playback speed of an audio CD. For example, a 48× drive can read a CD 48 times faster than an audio CD would be played.

CD-ROMs are a popular way to deliver digitized sound, images, and multimedia presentations that would be too bulky to put on ordinary diskettes. An entire encyclopedia or a collection of hundreds of pictures can fit on one disc. See also

LOW BOOK; ORANGE BOOK; ISO 9660; HIGH SIERRA FORMAT; MPC; MULTIMEDIA;

MULTISESSION CD; PHOTO CD.

CD-ROM XA (CD-ROM extended architecture) a set of extensions to the ISO 9660 format for compact disc data, allowing sound and video to be interleaved with computer data. The earlier format required sound, video, and computer files to be on separate tracks; XA removes this restriction. Virtually all CD-ROMs are now this type.

CD-RW (Compact Disc—ReWritable) a type of CD (compact disc) that can be recorded, erased, and reused by the user.

The surface of a CD-RW contains an alloy that can change back and forth between a bright crystalline state and a dark amorphous state; it can be switched from one state to the other by heating it to specific temperatures with a laser.

Because of the different material used in them, CD-RW discs cannot be read by some early-model CD-ROM or CD-R drives.

CDA see COMMUNICATIONS DECENCY ACT.

CDFS the CD-ROM file system under Windows 95 and later.

CE see WINDOWS (MICROSOFT).

Celeron a lower-cost version of the Intel Pentium II microprocessor, with less on-chip cache memory. Before its introduction, the Celeron was code-named Covington, to the delight of the authors of this book.

cell

1.a unit of information that forms a building block for a chart, database, or spreadsheet.

2.one of the sections into which a city or region is divided for cellular telephone service. Each cell is served by a different antenna tower.

FIGURE 53. Cell in a spreadsheet

cellular modem a MODEM that uses a cellular telephone for wireless connection to a computer network.

cellular telephone a wireless telephone that communicates through any of a number of antenna towers, each serving a particular “cell” of the city. The user is automatically transferred from cell to cell as he or she moves around. This contrasts with earlier mobile telephones that had to be within range of a particular tower in order to work.

center to cause type or other objects to appear in the middle of the line with equal amounts of space to either side.

This text

is set centered. Centered text is considered formal.

Contrast FLUSH LEFT; FLUSH RIGHT; JUSTIFICATION.